1. Field of the Invention
This invention relates to a flat screen autostereoscopic device for use in television, computer graphics, and the like viewing applications.
2. Prior Art
A simple, low cost autostereoscopic system capable of providing clear, bright, high resolution images has long been a goal of the television and computer graphics industry. Previous attempts to produce such a device have experienced the problems of high development costs, expensive equipment, e.g., vibrating components or lenses of various sorts, and bulky size. However, recent developments in the field of transparent flat screen image displays promise low cost, simple and compact autostereoscopic displays which use previously developed components.
U.S. Pat. No. 2,209,747 (Eisler) discloses placing an opaque screen with a plurality of transparent slits in front of a second screen which displays a stereoscopic pair of images made up of alternating strips. Each strip displays a thin vertical section of one of the images. The strips are arranged so that the first displays a section of the right eye image, the second a section of the left eye image, the third a section of the right eye image and so on. The screen with the transparent slits is placed at such a distance in front of the picture display that the observer sees only the right eye strips through the slits with his right eye and only the left eye strips through the slits with his left eye. This technique of displaying stereographic pictures is know as the Hess system. Devices using this technique are very cheap and easy to build. However, for good images the slits have to be very thin, relative to the opaque area between them, and thus a large fraction of the light coming from the display is blocked. This makes it difficult to obtain bright images.
U.S. Pat. No. 4,367,486 (Eichenlaub) discloses how three dimensional images can be viewed with appropriate perspective from many different angles. These images are created with a pinhole aperture or vertical slit that is scanned across a surface situated in front of a cathode ray tube (CRT) that displays images in rapid succession. The patent also discloses how the light blocking problems associated with small apertures could be eliminated by using a similar optical technique, but employing a moving light source in place of a pinhole and a surface that displays transparent images in place of the prior art CRT. This results in bright, clear three dimensional images.
U.S. Pat. No. 4,461,541 (Duthie) discloses an image display system and method that provides two separate and distinct images of a view scene for an observer. The images, taken from adjacent positions looking toward the target scene, are taken from relatively small, acute position angles with respect to the scene. These separate images are then encoded with different polarization in sequence for displaying on a television monitor. The images are prepared for viewing by an observer by focusing the monitored images onto a liquid crystal light valve. Collimated light from a coherent source addresses the light valve providing coherent output therefrom with the encoded images thereon. These images are brought to a Fourier plane and polarized or filtered selectively to provide separately encoded images in alternate frames of polarization. An observer wearing separately polarized lens and viewing an output screen sees a stereoscopic view of the imaged scene.
On the market today are several computer programs designed to be used with conventional CRT display and a set of "blinking" liquid crystal display (LCD) glasses which are worn by the user. Systems of this type are sold by Antics Software and Millenium Ltd of Great Britain. The LCD glasses are synchronized with the CRT screen in such a way that the left lens is transparent (and the right eye is opaque) when the beam is making the first scan of alternate rows, and the right eye is transparent (and the left eye opaque) when the beam is scanning the remaining rows. Thus, the viewer's left eye sees only a left eye image and the right eye sees only the right eye image, and the viewer perceives a scene with depth. The computer programs designed for use with such a system generate left eye images and right eye images on alternate rows of a computer monitor screen instead of on alternate columns of the screen.
There continues to be a need for a simple means of forming and viewing stereoscopic images.
Accordingly it is an object of this invention to provide a flat screen autostereoscopic display device.
It is a further object of this invention to provide a flat screen autostereoscopic display device which is low in cost and easy to manufacture.
Still another object of this invention is to provide a flat screen autostereoscopic display on which only alternate rows of pixels can be seen by the viewer's left eye and the remaining set of alternate rows can be seen only by the viewer's right eye.
Another object of this invention is to provide a flat screen autostereoscopic display device which is capable of providing large, bright, high resolution images and a wide field of view.